I took my truck with trailer to my local GMC service center. A service tech, that is an experienced RVer, took a test drive with my truck and trailer. After multiple gain adjustments, we agreed that 8.0 felt best and most secure.
We then hitched my trailer to a new 2012 GMC Sierra 2500HD CC SB Duramax which is similar to my truck, except mine is a 3500 and has the Z71 package. We took it out on the same route and performed the same tests. It too had the best braking with my trailer with the gain set at 8.0.
I do not know why, but the brake pedal felt "mushier" and had more travel than my 3500.
The braking response with both GM trucks with the ITBC were similar, but not as smooth as my previous BrakeSmart controller. The GM ITBC only has gain adjustment. The BrakeSmart provided additional adjustments like initial brake constant and power factor, in addition to gain.
The tech felt that I had become accustom to a more customizable controller. The GM controller is acceptable to most people. He could not explain delay I observed with the brake pedal vs manual lever when stationary. The system is hydraulic brake fluid pressure based. He felt that additional motion sensors do not activate immediate signal to brakes if stationary. He has not had to repair an ITBC before.
They offered to disable the ITBC and install the brake controller of my choice at no charge. I will play with the current system and decide if I think I'd be better off with a different controller. Too bad BrakeSmart is no longer being produced. That would be my first choice.
A friend performed the same test with his GM truck with ITBC and had the same result. When the trailer wheels are off the ground and spinning, the manual controller works instantly and a 2-3 second delay when the brake pedal is depressed.
The service manager and techs at Classic GMC of Carrollton treated me with respect and Were very friendly and helpful.
My conclusion: The ITBC in my truck functions as designed. It is good enough to make most people happy. GM could take a lesson from BrakeSmart and increase the available adjustments and improve their ITBC. They also should provide better information to the consumer of how their current product functions. Even the techs are in the dark.
'13 Excel Winslow 34IKE
'12 GMC Sierra 3500HD
Previous RV's: '03 MobileScout Titan 29DBS; '01 Sunnybrook Lite 2708 SLE; '99 Coleman Utah
Previous TV's: '02 Chevy Suburban 2500 8.1 4.10; '99 Chevy Express 1500 5.7